The majority of human thoughts, however, are by no means simple. Absolutely pure affection of course exists; but we very often find it tinged with pride or with selfishness, with jealousy or with animal passion. This means that at least two separate vibrations appear both in the mental and astral bodies--frequently more than two. The radiating vibration, therefore, will be a complex one, and the resultant thought-form will show several colours instead of only one. HOW THE VIBRATION ACTS These radiating vibrations, like all others in nature, become less powerful in proportion to the distance from their source, though it is probable that the variation is in proportion to the cube of the distance instead of to the square, because of the additional dimension involved. Again, like all other vibrations, these tend to reproduce themselves whenever opportunity is offered to them; and so whenever they strike upon another mental body they tend to provoke in it their own rate of motion. That is--from the point of view of the man whose mental body is touched by these waves--they tend to produce in his mind thoughts of the same type as that which had previously arisen in the mind of the thinker who sent forth the waves. The distance to which such thought-waves penetrate, and the force and persistency with which they impinge upon the mental bodies of others, depend upon the strength and clearness of the original thought. In this way the thinker is in the same position as the speaker. The voice of the latter sets in motion waves of sound in the air which radiate from him in all directions, and convey his message to all those who are within hearing, and the distance to which his voice can penetrate depends upon its power and upon the clearness of his enunciation. In just the same way the forceful thought will carry very much further than the weak and undecided thought; but clearness and definiteness are of even greater importance than strength. Again, just as the speaker's voice may fall upon heedless ears where men are already engaged in business or in pleasure, so may a mighty wave of thought sweep past without affecting the mind of the man, if he be already deeply engrossed in some other line of thought.